Diphallia (penile duplication (PD), diphallic terata, or diphallasparatus) is a medical condition in which a male infant is born with two penises. This is an extremely rare disorder with only approximately 100 cases of diphallia recorded since the first, reported by Johannes Jacob Wecker in 1609. Its occurrence is one in five and a half million men in the United States. Urine may be passed by both penises, by only one, or through some other aperture in the perineum. Most men with diphallus learn to use it for intercourse, though they cannot penetrate two partners at the same time.